In this study, a continuous online in situ attenuated total reflection Fourier- transform infrared (ATR-FTIR) spectroscopic technique was used to monitor the behavior of butyl xanthate adsorbed on CuO nanoparticle surfaces. A red-shift phenomenon, i.e., the absorption peak at 1200 cm-1 shifted to 1193 cm-1, was observed in the FTIR spectra. However, there was no obvious change in the peak intensity after desorption using ultrapure deionized water, indicating that butyl xanthate was chemisorbed on the CuO surface. We determined the order of the spectral intensity changes in the adsorption process using twodimensional (2D) IR spectroscopy. The 2D asynchronous spectra showed that the spectral intensity of the characteristic peak at 1265 cm-1 changed first. This may be attributable to the combined peaks of dixanthogen and xanthate molecular aggregates at the surfaces. The adsorption kinetics was studied by monitoring the intensity changes of the xanthate characteristic peak at 1200 cm-1. The adsorption kinetic data showed that the maximum chemisorption capacity of CuO for butyl xanthate was 529 mg·g-1, and the adsorption kinetics can be described by a pseudo-second-order reaction model.